In recent years, nuclear medicine imaging apparatuses, such as a gamma camera, a single photon emission computed tomography (SPECT) apparatus, and a positron emission tomography (PET) apparatus, have been known. The nuclear medicine imaging apparatus includes a detector that detects radiation. The nuclear medicine imaging apparatus detects radiation emitted from an isotope or a labeled compound which is introduced into body tissues using the detector and forms the image of the dose distribution of the radiation detected by the detector, thereby reconstructing a nuclear medicine image that provides the functional information of the body tissues.
For example, a radioactive drug including a labeled compound that is frequently introduced into tumor tissues is put into the body of the examinee. Then, the nuclear medicine imaging apparatus detects radiation emitted from the labeled compound for a predetermined period of time and reconstructs a nuclear medicine image including the distribution of the tumor tissues of the examinee into which the labeled compound is introduced.
In addition, in recent years, apparatuses have been proposed in which a nuclear medicine imaging apparatus that provides functional information is integrated with an X-ray computed tomography (X-ray CT) apparatus that provides shape information. For example, the following apparatuses have been proposed: a PET-CT apparatus in which a PET apparatus and an X-ray CT apparatus are integrated with each other; and a SPECT-CT apparatus in which a SPECT apparatus and an X-ray CT apparatus are integrated with each other.
When there is a failure in the detector of the nuclear medicine imaging apparatus, radiation is not detected. For example, there is a determination method that detects radiation emitted from a phantom including, for example, germanium(Ge)-68 and determines the detector that does not detect the radiation emitted from the phantom to be out of order.
However, the dose of radiation emitted from the phantom is small. Therefore, in the above-mentioned determination method, in some cases, it takes a long time to obtain a count required to determine whether there is a failure.